Update the way that pub determines DART_SDK on macos/linux.

Update the way that pub determines DART_SDK on macos/linux.
Committed: https://code.google.com/p/dart/source/detail?r=13037

[Bob Nystrom, 2012-09-28 17:38:04]

Assuming my question has an OK answer, LGTM.

https://codereview.chromium.org/10977083/diff/1/utils/pub/sdk/pub
File utils/pub/sdk/pub (right):

https://codereview.chromium.org/10977083/diff/1/utils/pub/sdk/pub#newcode1
utils/pub/sdk/pub:1: #!/bin/bash
I'm not a Unix expert. Will this cause problems for users that don't typically
use (or have?) bash as their shell?

[dgrove, 2012-09-28 17:49:29]

https://codereview.chromium.org/10977083/diff/1/utils/pub/sdk/pub
File utils/pub/sdk/pub (right):

https://codereview.chromium.org/10977083/diff/1/utils/pub/sdk/pub#newcode1
utils/pub/sdk/pub:1: #!/bin/bash
On 2012/09/28 17:38:04, Bob Nystrom wrote:
> I'm not a Unix expert. Will this cause problems for users that don't typically
> use (or have?) bash as their shell?
This only causes issues for people that don't have bash installed at all. 

Bash is available by default on both linux and macos. This just means that the
script will be executed by bash - it shouldn't cause problems for users that are
using other shells.

[Bob Nystrom, 2012-09-28 18:10:51]

SGTM. LGTM!